# 10.3 libevent實現http服務器 ```cpp #include <stdio.h> #include <stdlib.h> #include <unistd.h> //for getopt, fork #include <string.h> //for strcat //for struct evkeyvalq #include <sys/queue.h> #include <event.h> //for http //#include <evhttp.h> #include <event2/http.h> #include <event2/http_struct.h> #include <event2/http_compat.h> #include <event2/util.h> #include <signal.h> #define MYHTTPD_SIGNATURE "myhttpd v 0.0.1" //處理模塊 void httpd_handler(struct evhttp_request *req, void *arg) { char output[2048] = "\0"; char tmp[1024]; //獲取客戶端請求的URI(使用evhttp_request_uri或直接req->uri) const char *uri; uri = evhttp_request_uri(req); sprintf(tmp, "uri=%s\n", uri); strcat(output, tmp); sprintf(tmp, "uri=%s\n", req->uri); strcat(output, tmp); //decoded uri char *decoded_uri; decoded_uri = evhttp_decode_uri(uri); sprintf(tmp, "decoded_uri=%s\n", decoded_uri); strcat(output, tmp); //解析URI的參數(即GET方法的參數) struct evkeyvalq params; //將URL數據封裝成key-value格式,q=value1, s=value2 evhttp_parse_query(decoded_uri, &params); //得到q所對應的value sprintf(tmp, "q=%s\n", evhttp_find_header(&params, "q")); strcat(output, tmp); //得到s所對應的value sprintf(tmp, "s=%s\n", evhttp_find_header(&params, "s")); strcat(output, tmp); free(decoded_uri); //獲取POST方法的數據 char *post_data = (char *) EVBUFFER_DATA(req->input_buffer); sprintf(tmp, "post_data=%s\n", post_data); strcat(output, tmp); /* 具體的：可以根據GET/POST的參數執行相應操作，然后將結果輸出 ... */ /* 輸出到客戶端 */ //HTTP header evhttp_add_header(req->output_headers, "Server", MYHTTPD_SIGNATURE); evhttp_add_header(req->output_headers, "Content-Type", "text/plain; charset=UTF-8"); evhttp_add_header(req->output_headers, "Connection", "close"); //輸出的內容 struct evbuffer *buf; buf = evbuffer_new(); evbuffer_add_printf(buf, "It works!\n%s\n", output); evhttp_send_reply(req, HTTP_OK, "OK", buf); evbuffer_free(buf); } void show_help() { char *help = "http://localhost:8080\n" "-l <ip_addr> interface to listen on, default is 0.0.0.0\n" "-p <num> port number to listen on, default is 1984\n" "-d run as a deamon\n" "-t <second> timeout for a http request, default is 120 seconds\n" "-h print this help and exit\n" "\n"; fprintf(stderr,"%s",help); } //當向進程發出SIGTERM/SIGHUP/SIGINT/SIGQUIT的時候，終止event的事件偵聽循環 void signal_handler(int sig) { switch (sig) { case SIGTERM: case SIGHUP: case SIGQUIT: case SIGINT: event_loopbreak(); //終止偵聽event_dispatch()的事件偵聽循環，執行之后的代碼 break; } } int main(int argc, char *argv[]) { //自定義信號處理函數 signal(SIGHUP, signal_handler); signal(SIGTERM, signal_handler); signal(SIGINT, signal_handler); signal(SIGQUIT, signal_handler); //默認參數 char *httpd_option_listen = "0.0.0.0"; int httpd_option_port = 8080; int httpd_option_daemon = 0; int httpd_option_timeout = 120; //in seconds //獲取參數 int c; while ((c = getopt(argc, argv, "l:p:dt:h")) != -1) { switch (c) { case 'l' : httpd_option_listen = optarg; break; case 'p' : httpd_option_port = atoi(optarg); break; case 'd' : httpd_option_daemon = 1; break; case 't' : httpd_option_timeout = atoi(optarg); break; case 'h' : default : show_help(); exit(EXIT_SUCCESS); } } //判斷是否設置了-d，以daemon運行 if (httpd_option_daemon) { pid_t pid; pid = fork(); if (pid < 0) { perror("fork failed"); exit(EXIT_FAILURE); } if (pid > 0) { //生成子進程成功，退出父進程 exit(EXIT_SUCCESS); } } /* 使用libevent創建HTTP Server */ //初始化event API event_init(); //創建一個http server struct evhttp *httpd; httpd = evhttp_start(httpd_option_listen, httpd_option_port); evhttp_set_timeout(httpd, httpd_option_timeout); //指定generic callback evhttp_set_gencb(httpd, httpd_handler, NULL); //也可以為特定的URI指定callback //evhttp_set_cb(httpd, "/", specific_handler, NULL); //循環處理events event_dispatch(); evhttp_free(httpd); return 0; } ```